


The Mistakes of Men and Mermen

by kythen



Series: SASO2017 Bonus Round Fills [7]
Category: Haikyuu!!
Genre: Alternate Universe, M/M, Memory Loss, Merpeople, SASO2017, inconvenient spells, storming the wedding chapel
Language: English
Status: Completed
Published: 2017-06-11
Updated: 2017-06-11
Packaged: 2018-11-12 20:06:59
Rating: General Audiences
Warnings: No Archive Warnings Apply
Chapters: 1
Words: 1,114
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/11169138
Author URL: https://archiveofourown.org/users/kythen/pseuds/kythen
Summary: Oikawa needs to stop Iwaizumi from making the biggest mistake of his life. But first, he needs to get out of the sea.





	The Mistakes of Men and Mermen

**Author's Note:**

> > _Prompt: merman au where merman oikawa is friends with prince iwaizumi, but the cost of becoming human is iwaizumi forgetting who he is (temporarily? permanently? go wild lol)_
>> 
>> _bonus points if merpeople look not super human (cause like,, they're not ehe) and if it's happy or bittersweet >u< (doesn't have to be tho)_
>> 
>> _Other Tags: merpeople, oikawa making iwa-chan fall in love w him yet again, it's like playing a video game for the second time and it's all easy til u die to the final boss fight 80 times_

"I need a spell."  
  
"What for?"  
  
"Iwa-chan's getting married and I can't let him make that mistake."  
  
"Mistake? Says who?" Matsukawa raises an expressive eyebrow.  
  
"Says _me_ ," Oikawa tells him. "His best friend since forever."  
  
"Well, best friend since forever, who wouldn't be a mistake for our precious Prince Iwaizumi then?"  
  
"You?" Hanamaki interjects from the side, his too-many teeth sharp in his mouth as he grins.  
  
"I need to make him see the error of his ways." Oikawa folds his arms across his chest defensively.  
  
"Your way doesn't seem completely error-free either," Hanamaki points out. "You're asking Mattsun for a spell but do you even know what the effects of that would be?"  
  
"No, don't stop him," Matsukawa drawls, uncurling his tentacles from around the rock he had been perched on. "I really want to see this."  
  
"Me too actually but I don't really want to have to clean up after this." Hanamaki swims over to Matsukawa's side in lazy strokes and stage-whispers into the side of his head, "Things are going to get really messy."  
  
"We're not cleaning up after the both of them. We're just spectating," Matsukawa reassures him. "This is the most interesting thing I've seen since Iwaizumi first met Oikawa. It's like getting a sequel to your favourite play."  
  
Oikawa scowls at the both of them. "Will you two shut up already and help me get up there so I can fix Iwa-chan's big mistake?"  
  
"Sure," Matsukawa and Hanamaki say in unison, flashing twin grins at him.  
  
"But you're really not going to like the side-effects of this spell," Matsukawa adds.  
  


\---  


  
Oikawa Tooru is a handsome man.  
  
Not that he can really tell since he has no clue of what the human standards of beauty are. But Matsukawa and Hanamaki had called him the ugliest sea creature they had ever seen so he thinks that is how it works. Plus he has been getting looks of interest—not of the bad variety—from various people in town since he stepped into it so he can't look all that bad.  
  
He can't recognise himself in the windows he passes or the still pools of water he gazes into. Oikawa as a human being is a vastly different creature from Oikawa the merman with soft, brown curls where deadly spines had been and proper human eyes where solid black merman eyes had been.  
  
Matsukawa had warned him about the drastic appearance changes as well as the side-effects of the spell but Oikawa has faith in Iwaizumi. He has faith in their ten year long bond which had started when Iwaizumi had first fallen into the sea as a young child and Oikawa had saved him out of curiosity. It had been something like fate, like destiny, like an unbreakable bond forged between two unlikely creatures of the land and the sea. Their meeting had happened and Oikawa has utmost confidence in everything else that should follow.  
  
He bursts through the front doors of the chapel, strolling in past the shocked guards and dodging the one guard that actually has the sense of mind to stop him. Iwaizumi is there, along with a young maiden dressed entirely in white, decked out in his best ceremonial finery. Oikawa doesn't have a clue if Iwaizumi would be considered handsome or ugly or passable as a human being but he has always been endearing to Oikawa regardless of what shape or form he takes, even if he was hideous according to undersea standards.  
  
"Stop the wedding!" Oikawa shouts and it reverberates most satisfyingly through the chapel.  
  
The people gathered in pews gasp.  
  
A furrow forms between Iwaizumi's brows. "Who the hell are you?"  
  
"I know I look vastly different from my usual self but I'm Oikawa. Iwa-chan, I came from the sea to tell you that you are making a grave mistake."  
  
There is a pause. Then Iwaizumi's mouth falls open in shock and Oikawa's heart fills with hope. He knew that Iwaizumi would recognise him, regardless of changed form or spell side-effects.  
  
"Guards," Iwaizumi orders, his eyes fixed steelily on Oikawa, "arrest this lunatic."  
  


\---  


  
This isn't the sea. This isn't even land. It is a stone place of misery that Oikawa has somehow found himself in. They give him food and water through the bars but they laugh in his face when he demands to see Iwaizumi.  
  
_A shame about his face,_ the guards say outside his cell, _when the man is completely mad._  
  
"I want to go home," Oikawa says to the stone ceiling on his fifth day of imprisonment, lying flat on his back on the cool, dry floor. He misses the sea. He misses Matsukawa and Hanamaki despite all the awful pranks they put him through. He misses everybody.  
  
"I want to see Iwa-chan," Oikawa corrects himself, thinking about the reason why he had left behind all of that in the first place. He has to stop Iwaizumi from making the biggest mistake of his life. Oikawa's life. He hasn't even told Iwaizumi that he loves him.  
  
"And who is that supposed to be?" a familiar voice says from outside his door and Oikawa jerks up into a sitting position, swivelling his head towards the door.  
  
The locks creak and clank before falling away and the door swings open for Iwaizumi to step in. His ceremonial finery is gone, replaced by his usual plain tunic and breeches and sturdy leather armour.  
  
"Are you married yet?" Oikawa asks.  
  
Iwaizumi looks at him contemplatively. "No, not yet. There were some... complications after your dramatic objection."  
  
Oikawa sighs in relief.  
  
"Why are you so concerned about my marriage?" Iwaizumi asks him, his tone hard. "Who are you?"  
  
"Oikawa," he says. "Your marriage is a mistake."  
  
"Why is that so?"  
  
"Because..." Oikawa hesitates. "She's not the right one for you."  
  
"Are you a seer?" Iwaizumi's brows furrow.  
  
"No. I'm a merman."  
  
"A _what_?"  
  
"Merman turned man," Oikawa corrects. "Temporarily. I'll return to the sea when you see the error of your ways."  
  
"I'm leaving." Iwaizumi turns away from him. "You obviously need help from outside the castle."  
  
"Wait!" Oikawa rises from the floor, staggering from the sudden vertigo that overcomes him. "Don't you know who I am? I know I look completely different as a human being but I'm Oikawa. Oikawa Tooru. Don't you at least remember that?"  
  
Iwaizumi turns back and his eyes scan Oikawa's form from head to toe before he meets his gaze squarely. "I have never heard of that name in my life. I don't know who you are."  
  
"Goddamnit," Oikawa grits out as the cell door slams shut after Iwaizumi. "You weren't joking about the side-effects of that spell, Mattsun."

**Author's Note:**

> The unwritten continuation to this is that Matsukawa and Hanamaki end up saving Oikawa anyway and Oikawa throws himself repeatedly at Iwaizumi while evading capture in hopes that he will remember him.
> 
> Thanks for reading!
> 
> Find me here: [tumblr](http://kythen.tumblr.com) / [twitter](http://twitter.com/catcrowcalls)


End file.
